This chapter contains sections titled: Introduction Cell Cycle Regulation During Lateral Root Development Stemness of the Xylem-Pole-Associated Pericycle Auxin Signalling During Lateral Root Initiation Post-Transcriptional Feedback Mechanisms on Auxin Signalling Polar Auxin Transport Defines Lateral Root Boundaries Cytokinins Inhibit Lateral Root Development Brassinosteroids Regulate Auxin Transport Light Alters Auxin Sensitivity Conclusions and Perspectives